Set Asgard interfaces to passthrough
    
    This has already been used in production and is now imported
    as part of enrolling Orbit hypervisors into Salt.
    
    The Asgard VMs are currently exclusive guests on their hypervisors
    and the physical network cards support SR-IOV, hence passthrough
    mode was chosen.
    
    Signed-off-by: Georg Pfuetzenreuter <georg.pfuetzenreuter@suse.com>